diff --git a/CHANGELIST.md b/CHANGELIST.md
index f187393b..a1eb0d74 100644
--- a/CHANGELIST.md
+++ b/CHANGELIST.md
@@ -32,6 +32,7 @@
 - Update to DIC 20211101
 - Add protection sanitization for StarForce
 - Trim filenames for DVD protection from DIC
+- Fill out internal tests around Redump library
 
 ### 2.1 (2021-07-22)
 - Enum, no more
diff --git a/MPF.Test/RedumpLib/ExtensionsTests.cs b/MPF.Test/RedumpLib/ExtensionsTests.cs
index a83653e2..e6122b54 100644
--- a/MPF.Test/RedumpLib/ExtensionsTests.cs
+++ b/MPF.Test/RedumpLib/ExtensionsTests.cs
@@ -360,7 +360,7 @@ namespace MPF.Test.RedumpLib
         /// <summary>
         /// Check that every Region has a long name provided
         /// </summary>
-        /// <param name="mediaType">Region value to check</param>
+        /// <param name="region">Region value to check</param>
         /// <param name="expectNull">True to expect a null value, false otherwise</param>
         [Theory]
         [MemberData(nameof(GenerateRegionTestData))]
@@ -407,5 +407,154 @@ namespace MPF.Test.RedumpLib
         }
 
         #endregion
+
+        #region System
+
+        /// <summary>
+        /// RedumpSystem values that are considered markers and not real systems
+        /// </summary>
+        private static readonly RedumpSystem?[] _markerSystemTypes = new RedumpSystem?[]
+        {
+            RedumpSystem.MarkerArcadeEnd,
+            RedumpSystem.MarkerComputerEnd,
+            RedumpSystem.MarkerDiscBasedConsoleEnd,
+            RedumpSystem.MarkerOtherEnd,
+        };
+
+        /// <summary>
+        /// Check that every RedumpSystem has a long name provided
+        /// </summary>
+        /// <param name="redumpSystem">RedumpSystem value to check</param>
+        /// <param name="expectNull">True to expect a null value, false otherwise</param>
+        [Theory]
+        [MemberData(nameof(GenerateRedumpSystemTestData))]
+        public void RedumpSystemLongNameTest(RedumpSystem? redumpSystem, bool expectNull)
+        {
+            string actual = redumpSystem.LongName();
+
+            if (expectNull)
+                Assert.Null(actual);
+            else
+                Assert.NotNull(actual);
+        }
+
+        // TODO: Re-enable the following test once non-Redump systems are accounted for
+
+        /// <summary>
+        /// Check that every RedumpSystem has a short name provided
+        /// </summary>
+        /// <param name="redumpSystem">RedumpSystem value to check</param>
+        /// <param name="expectNull">True to expect a null value, false otherwise</param>
+        //[Theory]
+        //[MemberData(nameof(GenerateRedumpSystemTestData))]
+        //public void RedumpSystemShortNameTest(RedumpSystem? redumpSystem, bool expectNull)
+        //{
+        //    string actual = redumpSystem.ShortName();
+
+        //    if (expectNull)
+        //        Assert.Null(actual);
+        //    else
+        //        Assert.NotNull(actual);
+        //}
+
+        // TODO: Test the other attributes as well
+        // Most are bool checks so they're not as interesting to have unit tests around
+        // SystemCategory always returns something as well, so is it worth testing?
+
+        /// <summary>
+        /// Generate a test set of RedumpSystem values
+        /// </summary>
+        /// <returns>MemberData-compatible list of RedumpSystem values</returns>
+        public static List<object[]> GenerateRedumpSystemTestData()
+        {
+            var testData = new List<object[]>() { new object[] { null, true } };
+            foreach (RedumpSystem? redumpSystem in Enum.GetValues(typeof(RedumpSystem)))
+            {
+                // We want to skip all markers for this
+                if (_markerSystemTypes.Contains(redumpSystem))
+                    continue;
+
+                testData.Add(new object[] { redumpSystem, false });
+            }
+
+            return testData;
+        }
+
+        #endregion
+
+        #region System Category
+
+        /// <summary>
+        /// Check that every SystemCategory has a long name provided
+        /// </summary>
+        /// <param name="systemCategory">SystemCategory value to check</param>
+        /// <param name="expectNull">True to expect a null value, false otherwise</param>
+        [Theory]
+        [MemberData(nameof(GenerateSystemCategoryTestData))]
+        public void SystemCategoryLongNameTest(SystemCategory? systemCategory, bool expectNull)
+        {
+            string actual = systemCategory.LongName();
+
+            if (expectNull)
+                Assert.Null(actual);
+            else
+                Assert.NotNull(actual);
+        }
+
+        /// <summary>
+        /// Generate a test set of SystemCategory values
+        /// </summary>
+        /// <returns>MemberData-compatible list of SystemCategory values</returns>
+        public static List<object[]> GenerateSystemCategoryTestData()
+        {
+            var testData = new List<object[]>() { new object[] { null, true } };
+            foreach (SystemCategory? systemCategory in Enum.GetValues(typeof(SystemCategory)))
+            {
+                if (systemCategory == SystemCategory.NONE)
+                    testData.Add(new object[] { systemCategory, true });
+                else
+                    testData.Add(new object[] { systemCategory, false });
+            }
+
+            return testData;
+        }
+
+        #endregion
+
+        #region Yes/No
+
+        /// <summary>
+        /// Check that every YesNo has a long name provided
+        /// </summary>
+        /// <param name="yesNo">YesNo value to check</param>
+        /// <param name="expectNull">True to expect a null value, false otherwise</param>
+        [Theory]
+        [MemberData(nameof(GenerateYesNoTestData))]
+        public void YesNoLongNameTest(YesNo? yesNo, bool expectNull)
+        {
+            string actual = yesNo.LongName();
+
+            if (expectNull)
+                Assert.Null(actual);
+            else
+                Assert.NotNull(actual);
+        }
+
+        /// <summary>
+        /// Generate a test set of YesNo values
+        /// </summary>
+        /// <returns>MemberData-compatible list of YesNo values</returns>
+        public static List<object[]> GenerateYesNoTestData()
+        {
+            var testData = new List<object[]>() { new object[] { null, false } };
+            foreach (YesNo? yesNo in Enum.GetValues(typeof(YesNo)))
+            {
+                testData.Add(new object[] { yesNo, false });
+            }
+
+            return testData;
+        }
+
+        #endregion
     }
 }
diff --git a/RedumpLib/Converters/YesNoConverter.cs b/RedumpLib/Converters/YesNoConverter.cs
index 001eb29c..a5ab3cbd 100644
--- a/RedumpLib/Converters/YesNoConverter.cs
+++ b/RedumpLib/Converters/YesNoConverter.cs
@@ -8,16 +8,16 @@ namespace RedumpLib.Converters
     /// <summary>
     /// Serialize YesNo enum values
     /// </summary>
-    public class YesNoConverter : JsonConverter<YesNo>
+    public class YesNoConverter : JsonConverter<YesNo?>
     {
         public override bool CanRead { get { return false; } }
 
-        public override YesNo ReadJson(JsonReader reader, Type objectType, YesNo existingValue, bool hasExistingValue, JsonSerializer serializer)
+        public override YesNo? ReadJson(JsonReader reader, Type objectType, YesNo? existingValue, bool hasExistingValue, JsonSerializer serializer)
         {
             throw new NotImplementedException();
         }
 
-        public override void WriteJson(JsonWriter writer, YesNo value, JsonSerializer serializer)
+        public override void WriteJson(JsonWriter writer, YesNo? value, JsonSerializer serializer)
         {
             JToken t = JToken.FromObject(value.LongName() ?? string.Empty);
             t.WriteTo(writer);
diff --git a/RedumpLib/Data/Extensions.cs b/RedumpLib/Data/Extensions.cs
index 2f2169de..3f510133 100644
--- a/RedumpLib/Data/Extensions.cs
+++ b/RedumpLib/Data/Extensions.cs
@@ -2138,7 +2138,7 @@ namespace RedumpLib.Data
         /// </summary>
         /// <param name="yesno"></param>
         /// <returns></returns>
-        public static string LongName(this YesNo yesno) => AttributeHelper<YesNo>.GetAttribute(yesno)?.LongName ?? "Yes/No";
+        public static string LongName(this YesNo? yesno) => AttributeHelper<YesNo?>.GetAttribute(yesno)?.LongName ?? "Yes/No";
 
         /// <summary>
         /// Get the YesNo enum value for a given string
diff --git a/RedumpLib/Data/SubmissionInfo.cs b/RedumpLib/Data/SubmissionInfo.cs
index bac1d0e0..9fd749d2 100644
--- a/RedumpLib/Data/SubmissionInfo.cs
+++ b/RedumpLib/Data/SubmissionInfo.cs
@@ -296,7 +296,7 @@ namespace RedumpLib.Data
     {
         [JsonProperty(PropertyName = "d_edc", NullValueHandling = NullValueHandling.Ignore)]
         [JsonConverter(typeof(YesNoConverter))]
-        public YesNo EDC { get; set; }
+        public YesNo? EDC { get; set; }
 
         public object Clone()
         {
@@ -376,11 +376,11 @@ namespace RedumpLib.Data
     {
         [JsonProperty(PropertyName = "d_protection_a", NullValueHandling = NullValueHandling.Ignore)]
         [JsonConverter(typeof(YesNoConverter))]
-        public YesNo AntiModchip { get; set; }
+        public YesNo? AntiModchip { get; set; }
 
         [JsonProperty(PropertyName = "d_protection_1", NullValueHandling = NullValueHandling.Ignore)]
         [JsonConverter(typeof(YesNoConverter))]
-        public YesNo LibCrypt { get; set; }
+        public YesNo? LibCrypt { get; set; }
 
         [JsonProperty(PropertyName = "d_libcrypt", NullValueHandling = NullValueHandling.Ignore)]
         public string LibCryptData { get; set; }